1. Field of the Invention
The present invention relates to a hinge structure for coupling a first member, such as an image scanner cover, relatively swingably and separably to a second member, such as an image scanner body.
2. Description of the Relevant Art
Various image scanners for reading image information from a copy and converting the image information into an electric signal are widely used in many applications such as the entry of image information into a computer. One typical type of image scanner comprises a body having on its upper surface a horizontal copy support plate for placing a copy to be read thereon and a cover, swingably coupled to the body by hinges, for covering the copy support plate. The copy support plate is usually in the form of an elongate rectangular transparent glass panel. The body houses a light source for applying light, from below the copy support plate, to a copy which is placed on the copy support plate with an image side of the copy facing downwardly. An optical system is provided for focusing light reflected from the image side of the copy onto an image focusing surface, and a photoelectric transducer, such as a CCD is positioned in the image focusing surface for generating an electric signal representing the focused image.
The cover serves as a light shield for preventing the light emitted by the light source from reaching the eyes of the user of the image scanner. It also serves as a copy holder for holding the copy, which is often a paper sheet, intimately down against the copy support plate so that the image be used to is well focused on the image focusing surface. In addition, the cover may clamp the copy securely between the cover and the copy support plate to prevent accidental displacement of the copy. In many image scanners the cover is in the form of an elongate plate or board and has a size large enough to cover the entire copy support surface area of the copy support plate. One side of the cover is swingably joined to the body through hinges for angular movement between a closed position (in which the cover lies on the copy support plate, thus covering the copy support surface area), and an open position (in which the side of the cover, opposite to the hinged side, is lifted to allow the user to access the copy on the copy support plate).
The above cover construction is well known in the art, but suffers a problem in relation to the size of the copy. It is often experienced by the user of the image scanner that an image to be read is positioned in only a portion of a large copy, and the entire size of the copy is about the same as or larger than the size of the upper surface of the body of the image scanner. In such a case, the cover interferes with the copy, tending to obstruct the image so that it cannot be positioned desirably in the copy support surface area. To remove such an obstruction, it is desirable that the cover be separated and removed from the body.
The hinges, through which the cover is swingably coupled to the body, may be constructed such that they allow the cover to be separated from the body. The separable hinge structure is more desirable from the standpoint of structural simplicity than other covers which have a structure, other than the hinges, for severing the cover from the body. Desirably or preferably, the separable hinge structure has to meet the following requirements:
1. Members of the hinges which remain on the body after the cover is separated from the body should be small in dimensions, particularly height, in order to facilitate the handling of large-size copies over the copy support surface area of the body.
2. For reliable opening and closing operation of the cover, the cover should not accidentally be separated from the body when the cover is opened and closed by the user while the image scanner is in normal use.
3. For better efficiency, the user of the image scanner himself should easily be able to separate the cover from or couple the cover to the body without assistance of service personnel.